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Earth^39 Dry land covers just under one-third of the Earth’s surface. It is made up mostly of seven huge landmasses called conti ...
Alaska^ Cu rrent^ North^ Pacific^ Curre nt^ North Equatorial Current Equatorial Countercurrent South (^) Equ atorial Countercurr ...
Earth^41 The ocean floor has landscapes as dramatic and varied as those of the Earth’s continents. Some parts have deep chasms, ...
42 Earth An island is an area of land smaller than a continent and entirely surrounded by water. Islands range from single rocks ...
Earthquakes are vibrations triggered by sudden rock movements deep underground, which cause the Earth’s surface to shake. Major ...
44 Earth A volcano is a vent or weak spot in the Earth’s crust through which magma (hot, melted rock) escapes as . LAVA. In some ...
Earth^45 A mountain is a steep-sided mass of rock, rising at least 600 m (2,000 ft) above sea level. Mountains are found on land ...
46 Earth The Earth’s crust is made of rocks, and rocks are made of natural substances called. MINERALS. There are three main typ ...
Earth^47 WHAT ARE THE MOST VALUABLE MINERALS? Some of the most valuable minerals are ores – minerals that contain metals such as ...
48 Earth Soil is one of Earth’s most precious resources. It provides the support and nourishment that plants need in order to gr ...
Earth^49 EXOSPHERE Situated 450–900 km (280–560 miles) above the Earth’s surface, the exosphere is the atmosphere’s outer layer ...
50 Earth HOW DO EXPERTS PREDICT THE WEATHER? Meteorologists receive information about air temperature, wind speeds, clouds, and ...
Earth^51 Winds are moving currents of air, which can blow over a small local area or over a much larger region. Global winds hel ...
52 Earth The Earth is unusual among the planets in our Solar System in having an atmosphere that contains moisture. Moisture in ...
Earth^53 HOW DOES HAIL FORM? Hail forms in cumulonimbus (storm) clouds that contain powerful, vertical air currents. Water dropl ...
54 Earth A storm is a bout of severe weather, with strong winds roaring at more than 88 km/h (55 mph), lightning flashes, thunde ...
WHAT CAUSES LANDSLIDES? Landslides often strike after heavy rain or snow has fallen. Loose soil and rocks begin to trickle downh ...
56 Earth HOW DO RIVERS SHAPE THE LANDSCAPE? A river’s load scours the river bed, deepening its channel. The speed of the flowing ...
Caves are hollow spaces carved into hillsides or underground by the action of water and the wind. On coasts, pounding waves some ...
58 Earth FIND OUT MORE. Antarctica 276 • Erosion 55 • Mountains 45 • Prehistoric Life 77 At the poles and on high mountains, vas ...
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